Especially after Karthus' long lore has arrived...
Is he really evil? He legitamately believes taht what he is doing is right - hell, the argument can even be made that it is. I would take immortality, invulnerability, and freedom from mortality/pain if I could. Sure, he's a bit messed in the head, but he isn't really obsessed with DEATH as his quotes seems to reflect - more undeath.
Thoughts?